Mark,

I am looking at the fine work by George Eichelberger

Railway Equipment Drawings and Photographs - Volume 1, Book 1 - 40'
All-Steel Box Cars" which I really recommend if you are doing

modeling of Southern box cars. I note this as I am NOT an expert

boards but only off this to help.

On page 146 reference is made to "steel Morton products

latitudinal running boards (roof walks)."

On page 156 there is a detailed drawing of the running boards also
referencing Morton as the supplier. On this drawing it shows a

the boards showing an arrangement of larger circles surrounded by

smaller circles.

I hope this helps.

Allen Cain